As the world continues to grow and expand, construction and the harvesting of natural resources has increased exponentially. These activities impact the environment. Specifically, some of the Earth's greatest landscapes are threatened by increased road construction, oil and gas exploration, and mining. Soil erosion, run-off, and chemicals leaching into the soil or ground water supplies are just a few of the many things that can negatively impact the environment. Because impervious surfaces (parking lots, roads, buildings, compacted soil) do not allow rain to infiltrate into the ground, more runoff is generated than in the undeveloped condition. This additional runoff can erode watercourses (streams and rivers) as well as cause flooding after the storm water collection system is overwhelmed by the additional flow. Because the water is flushed out of the watershed during the storm event, little infiltrates the soil, replenishes groundwater, or supplies stream base flow in dry weather. The negative effect of these events can be greatly increased when improper or outdated erosion and sediment control systems are put into place.
Current erosion and sediment control systems include the use of silt fencing, sand bags, and storm drain covers. Silt fences are often perimeter controls, typically used in combination with sediment basins and sediment traps, as well as erosion controls, which are designed to retain sediment in place where soil is being disturbed by construction processes. A typical fence consists of a piece of synthetic filter fabric (also called a geotextile) stretched between a series of wooden or metal fence stakes along a horizontal contour level. The stakes are installed on the downhill side of the fence, and the bottom edge of the fabric can be trenched into the soil and backfilled on the uphill side, although it is quite difficult to move the trenched “soil” from the downside to the upside of the trench. The design/placement of the silt fence should create a pooling of runoff, which then allows sedimentation to occur. Water can seep through the silt fence fabric, but the fabric often becomes “blocked off” with fine soil particles. Sediment is captured by silt fences primarily through ponding of water and settling, rather than filtration by the fabric. Sand and silt tends to clog the fabric, and then the sediments settle in the temporary pond. Silt fence fabrics (geotextiles) tested in laboratory settings have shown to be effective at trapping sediment particles. Although there have been few field tests of silt fences installed at construction sites, these tests have shown generally poor results. Other studies and articles about silt fence usage and practice document problems with installation and maintenance, implying poor performance.
Other forms of sediment control and erosion prevention include the use of sandbag barriers, fiber rolls, and storm drain inlet protection. Sandbag barriers may prevent or divert the flow of contaminated water away from a water source or storm drain, but they fail to provide a filter for removing contaminants from the water and allowing clean water to pass through. Fiber rolls are generally a temporary erosion control and sediment control device used on construction sites to protect water quality in nearby streams, rivers, lakes and seas from sediment erosion. Typically they will be made of straw, coconut fiber or similar material formed into a tubular roll. While these fiber rolls do provide a basic form of filtration, they generally provide only minimal filtration and are not reusable. Some of the disadvantages of fiber rolls are that they may be difficult to move once they become saturated with water, they should not be used on very steep land, and if the rolls are not properly staked into the ground, they may be carried away by high flows. Storm drain inlet protections typically only include a steel grate with large openings. While they prevent large items from entering a storm drain or inlet, they fail to prevent soil sediment and other contaminants from entering the drain. A sand barrier or fiber roll may be placed around a storm drain inlet to provide additional protection, but these items typically provide either extremely slow flow rates or else minimal filtration.
Therefore, there exists a need in the art for an apparatus and system that allows for improved filtration and removal of sediment and other pollutants from water, as well as providing an increased flow rate through the filtration system.